Higgs Decay Rates Measured Simultaneously at Future Collider

Physicists have outlined a precise method for measuring the decay rates of the Higgs boson into pairs of W and Z bosons at a future particle collider. The analysis targets the proposed Future Circular Collider electron-positron (FCC-ee) machine, focusing on a specific production process where the Higgs is created alongside a Z boson.

This measurement is central to understanding the Higgs boson's interactions with the fundamental forces of nature. In particular, the couplings of the Higgs to the W and Z bosons are crucial for a model-independent determination of its total decay width, a key property.

The Hadronic Channel Strategy

The study concentrates on events where all involved particles decay into quarks, which manifest as jets of hadrons in the detector. Both the Higgs boson and the associated Z boson from its production are analyzed in their fully hadronic decay modes. For a Higgs decaying to WW or ZZ, and with the associated Z also decaying hadronically, this results in a final state containing six distinct jets.

This channel offers a high-statistics pathway for study. The large branching fraction of the Higgs to WW provides many candidate events. For the rarer Higgs to ZZ decay, the high probability of Z bosons decaying hadronically helps compensate for the lower signal rate.

Simultaneous Extraction and Reconstruction

A significant challenge is the substantial kinematic overlap between the WW and ZZ final states. Their signal strengths must therefore be extracted simultaneously in the analysis. Researchers employ advanced jet-clustering algorithms and dedicated techniques to pair the correct jets together, reconstructing the decaying gauge bosons and separating the two signal components.

The proposed measurement assumes a collider center-of-mass energy of 240 GeV and an integrated luminosity of 10.8 inverse attobarns of data. Under these conditions, the expected precision on the combined production cross-section and branching fraction is remarkably high.

Projected Precision

The analysis forecasts the following relative uncertainties for the key measurements:

These projected uncertainties demonstrate the potential power of the FCC-ee for making ultra-precise measurements of fundamental Higgs properties. The study provides a detailed roadmap for exploiting the fully hadronic channel to constrain the Higgs boson's behavior with unprecedented accuracy.